Fauna of Europe
Fauna of Europe is all the animals living in Europe and its surrounding seas and islands. Since there is no natural biogeographic border in the east and south between Europe and Asia, the term "fauna of Europe" is somewhat elusive. Europe is the western part of the Palearctic ecozone (which in turn is part of the Holarctic). Lying within the temperate region, (north of the equator) the wildlife is not as rich as in warmer regions.
Origins of european fauna:
The formation of the European fauna began in the Mesozoic with the splitting of Laurasian supercontinent and was eventually separated from both North America and Asia in the Eocene. During the early Cenozoic, the continents approached their present configuration, Europe experienced periods of land connection to North America via Greenland, resulting in colonization by North American animals. In these times, higher sea levels sometimes fragmented Europe into island subcontinents. As time passed, sea levels fell, with seas retreating from the plains of western Russia, establishing the modern connection to Asia (Priabonian). Asian animal species then colonized Europe in large numbers, and many endemic European lineages (e.g. primates) died out.
Glaciation during the most recent ice age and the presence of man affected the distribution of European fauna. As for the animals, in many parts of Europe most large animals and top predator species have been hunted to extinction. The woolly mammoth was extinct before the end of the Neolithic period. Tree species spread outward from refugia during interglacial periods, but in varied patterns, with different trees dominating in different periods. Insects, on the other hand, shifted their ranges with the climate, maintaining consistency in species for the most part throughout the period. Their high degree of mobility allowed them to move as the glaciers advanced or retreated, maintaining a constant habitat despite the climatic oscillations. Mammals recolonized at unstable rates. Brown bears, for example, moved quickly from refugia with the receding glaciers, becoming one of the first large mammals to recolonize the land. The last glacial period ended about 10,000 years ago, resulting in the present distribution of ecoregions.
Northern hemisphere glaciation during the last ice age:
The cyclic changes of the Pleistocene between cold and warm periods resulted in antagonistic responses within two different groups of organisms: one expanding during the warm periods and retracting during the cold phases and another with opposed responses (the latter group is composed of so-called arctic and alpine species).
The north-eastern Atlantic Ocean can be divided into two main biogeographic regions - the Lusitanian (west of British Isles, Bay of Biscay, Iberian coast until Gibraltar), and Northern European Seas (including North sea and Baltic sea). A clearly distinct area is also the Macaronesian islands region. The North sea is home to about 230 species of fish. Cod, haddock, whiting, saithe, plaice, sole, mackerel, herring, pouting, sprat, and sandeel are common and target of commercial fishing. Due to the various depths of the North Sea trenches and differences in salinity, temperature, and water movement some fish reside only in small areas of the North Sea (e.g. Blue-mouth redfish, Rabbitfish). Of crustaceans, Norway lobster, and deep-water prawns and brown shrimp are commercially fished. The coasts provide breeding habitat for dozens of bird species. Tens of millions of birds make use of the North Sea for breeding, feeding, or migratory stopovers every year. Populations of Northern fulmars, Black-legged Kittiwakes, Atlantic puffins, razorbills, and a variety of species of petrels, gannets, seaducks, loons, cormorants, gulls, auks, and terns, and other seabirds make these coasts popular for birdwatching.
The Baltic Sea is an ecological island, isolated from other brackish seas by land and fully marine seas. The low salinity of the Baltic sea has led to the evolution of many slightly divergent species, such as the Baltic Sea herring, which is a smaller variant of the Atlantic herring. The most frequent benthic species are Saduria entomon and Monoporeia affinis, which are originally a freshwater species. A great part of its bottom is without oxygen and without animal life. The Baltic sea and North Sea are also home to a variety of marine mammals (Common seals, grey seals).
Europe contains several important freshwater ecoregions, including the heavily developed Rivers of Europe, the Rivers of Russia, which flow into the Arctic, Baltic, Black, and Caspian seas. There are about 15,000 European freshwater known animal species.
80-90 percent of Europe was once covered by forest. It stretched from the Mediterranean Sea to the Arctic Ocean. Though over half of Europe's original forests disappeared through the centuries of deforestation, Europe still has over one quarter of its land area as forest, such as the boreal forests of Scandinavia and Russia, mixed rainforests of the Caucasus and the Cork oak forests in the western Mediterranean.
About 100,000 invertebrate species (including insects) are known from Europe. The marine species richness is greatest in the Mediterranean with 600 sponge species (45% of them endemic), 143 known species of Echinoderms and about 500 species of Cnidarians. There are about 1500 species of non-marine molluscs in Europe. The marine fauna is the richest in the Mediterranean region (2000 marine mollusc species). Almost 1000 species of oligochaetes live in Europe.
Europe has 344 fresh-water fish species. Some 277 fish species have been introduced to Europe, and over one-third of Europe’s current fish fauna is composed of introduced species, whereas more than a third of Europe's freshwater fish species are at risk of extinction, according to new data released by the World Conservation Union (IUCN).
The list of European birds is about 800 species long. About half of the European birds are passerines of the songbirds suborder.
European mammal fauna consists of 270 species, 78 of them endemic to Europe (15% of them are threatened with extinction and 27% have been identified as declining). There are no endemic mammal orders in the region.
Fauna of Great Britain:
The island of Great Britain, along with the rest of islands known as the British Isles, has a largely temperate environment. Animal diversity is little due to several factors including; the size of the land area, seasonal changes and the age of the habitats found on the islands.
The fact that Great Britain has such a small area means that the number of species that can develop is severely limited because there is not enough land mass to support extensive animal diversity. The environment and the ecology is also very young due to the appearance of an Ice Age, which means that there has been much less time for such diversity to develop. In most of Great Britain there is a temperate climate which receives high levels of precipitation and medium levels of sunlight. The seasonal changes that occur across the country means that plants have to cope with many changes linked to levels of sunlight, and this has led to a lack of plant diversity. Ultimately this has limited animal speciation and diversification because there are less edible types of vegetation in the habitats found on the islands.
Since the mid eighteenth century, Great Britain has gone through industrialisation and increasing urbanisation. A DEFRA study from 2006 suggested that 100 species have become extinct in the UK during the 20th century, about 100 times the background extinction rate. This has had a major impact on indigenous animal populations. Birds in particular are becoming more rare and habitat loss has affected larger mammalian species. Some species have however adapted to the increasing urban environment, particularly the Red Fox, which is the most successful urban mammal after the Brown Rat.
Ďaľšie referáty z kategórie
Fauna and flora of Europe
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